Hydraulic clutch brake for wet plate clutches

ABSTRACT

A vehicle clutch having clutch plate and disc members within a sealed clutch housing operative to effect engagement and disengagement of the clutch by operation of a disengaging member. An oil pump structurally associated with the disengaging member provides oil for the clutch through a guide wheel which is axially movable together with the disengaging member. In the engaged position, a deflector directs an oil stream from the guide wheel through openings to the clutch plate and disc members, while in the disengaged position a pump wheel is provided with pump impeller blades to deflect the oil stream from the guide wheel away from the clutch plate and disc members.

The present invention relates generally to clutches for vehicles andmore particularly to clutches wherein clutch plate means rotating withina sealed clutch housing are operatively engaged with clutch discs whichmay be actuated by means of a spring member controlled by a disengagingmember of the clutch. The clutch also comprises an oil pump which isassociated with the disengaging member by means of which an oil streammay be applied against the clutch discs through a deflector which isstructurally associated with the clutch plate means.

In wet plate clutches or wet operating clutches, as compared with dryplate clutches, a plurality of discs must be provided because of the lowfriction value developed. In such wet plate clutches, an oil stream isusually fed to the clutch discs for cooling. Due to the fact that aplurality of clutch discs are involved, the rotating mass which must bebraked during each shifting step by synchronization of a transmission isenlarged.

The oil stream which is fed to the clutch discs simultaneously generatesa drag moment which can operate to negatively affect the shiftingprocess. In order to maintain this drag moment as small as possible, theoil stream should be diverted or deflected when the clutch is in thedisengaged condition.

The large inertia moment of the clutch discs together with theadditional drag moment developed by the oil stream can have a negativeeffect upon the ease with which shifting may be effected due to thelonger shifting periods involved or because of shifting difficulties.

In German Auslegeschfrit No. 23 45 774, there is disclosed a clutchbrake with an axially movable braking member for braking the rotatingmass of the clutch in order to improve the ease with which shifting maybe accomplished. However, it has been found that clutches of this typeof the prior art result in increased expenditures.

Accordingly, the present invention is directed toward provision of aclutch braking mechanism for wet plate clutches involving only limitedadditional expenditures whereby the rotating mass of the clutch discscan be effectively braked and a drag moment due to the oil stream insaid clutches can be eliminated to a substantial extent.

SUMMARY OF THE INVENTION

Briefly, the present invention may be described as a clutch for vehicleswhich comprises a clutch housing having a guide wheel arranged thereinwhich is connected with a disengaging member of the clutch and which isaxially movable together with the disengaging member. Furthermore, theinvention includes a pump wheel which is related with an oil deflectorof the clutch plate. In the disengaged state, the oil stream for theclutch may be deflected by means of the pump wheel at an angle leadingaway from the clutch plate and the clutch discs. With these measures, aclutch brake is created which is controlled by the disengaging member independence upon its path of movement. When the clutch is disengaged, theoil stream is deflected and accelerated by the elements constituting theclutch brake from the direction of rotation of the clutch plate and theclutch discs. The work which is performed thus acts as a braking torqueon the clutch discs. At the same time, the oil stream to the clutchdiscs is interrupted and thus the drag moment is prevented.

Additional expenditures to achieve this braking torque are relativelysmall and consist essentially only in coupling the guide wheel with thesliding sleeve of the disengaging member and of the additional pumpwheel which is advantageously welded by spot welding to the deflectorwhich is connected with the clutch plates.

In accordance with another aspect of the invention, there is provided anarrangement wherein the pump wheel guides the oil stream in thedisengaged condition out of the clutch and wherein the guide wheel isarranged concentrically in the clutch and conveys the oil streamradially outwardly with the oil stream being deflected also in an axialdirection with the clutch in the disengaged state. The pump wheel isprovided at its radial outer periphery with an axial curvature withwhich the oil stream may be deflected in the axial direction when theclutch is in the disengaged state, with this axial curvature lying inthe region of the clutch discs.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated and described a preferredembodiment of the invention.

DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a sectional view showing a wet plate clutch having the clutchbraking system in accordance with the invention, with the clutch shownin the engaged state; and

FIG. 2 is a sectional view showing the clutch of FIG. 1 in thedisengaged state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is shown a clutch 1 having aplurality of clutch discs 4 which are connected on the radially outerside of a clutch plate 3. In the embodiment depicted, three clutch discs4 are provided with the arrangement including a clutch housing 2.

The clutch discs 4 are held in engagement by a diaphragm spring 7 bymeans of a pressure plate 5. The diaphragm spring 7 is radially centeredby a centering bolt 9 with respect to the pressure plate 5 and extendson its radially inner side with diaphragm spring tongues 8.

A disengaging member 13 is provided with an axially slidable release rim15 which acts on the radially inwardly located ends of the diaphragmspring tongues 8. In order to compensate for possible motor vibrations,a vibration damper 6 is assigned to the clutch plate 3. A deflector 10is located radially between the vibration damper 6 and the clutch discs4, with the deflector 10 being arranged at the clutch plate 3 and beingpreferably riveted together with the clutch discs 4 in order thus torotate together with the clutch plate 3.

Openings 26 through which oil may pass are provided in the deflector 10.Furthermore, guide discs 28 are provided having therein guide openings27 through which oil may also pass. As a result, the oil may reach theclutch discs 4 through the openings 26 and the guide openings 27.

The deflector 10 extends in an axially displaced arrangementapproximately parallel to the clutch plate 3. On the side thereof whichfaces away in the axial direction from the clutch plate 3, there isprovided a pump wheel 12 which is rigidly connected for rotation withthe deflector 10, preferably by means of welding joints 30. The pumpwheel 12 has at its radially outer periphery an axial curvature whichfaces away from the deflector 10 and thus away from the clutch plate 3.Pump impeller blades 29 extending perpendicularly to the pump wheel 12are arranged in order to guide oil radially outwardly into the region ofthe axial curvature 25. The axial curvature 25 adjoins the clutch discs4 and the disc guidances 28 radially inwardly thereof.

In the disengaging member 13 which acts on the radially inwardly locateddiaphragm spring tongues 8 there is arranged a rotatable sleeve 14 whichprojects into the clutch 1 up to proximity with the clutch plate 3. Atthe end adjoining the clutch plate 3, a guide wheel 11 is rigidlyconnected for rotation with the rotatable sleeve 14, preferably by ariveted connection.

An oil pump 16, which may be a so-called half-moon pump, is structuallyassociated with the disengaging member 13. The oil pump 16 is attached,for example, at a guide part 23 of the disengaging member 13 and it isalso driven by the motor of the apparatus. The pump has a suction side17 which faces the clutch 1 and a pressure side 18 which faces atransmission housing (not shown) with a feed wheel 19 operating to feedoil from the suction side 17 to the pressure side 18.

An oil stream is thus developed by the oil pump 16 which flows throughthe rotatable sleeve 14 to the guide wheel 11 into the clutch housing 2.The rotatable sleeve 14 is continuously rotated on the transmissionshaft 24. The guide wheel 11 also rotates so long as the rotatablesleeve 14 and the oil pump 16 rotate. This results in an uninterruptedradially outwardly directed oil stream 20 which, when viewed from above,will have an approximately planar appearance in the axial direction. Theoil stream 20 penetrates the openings 26 and the guide openings 27 atthe clutch discs 4 and operates to cool and lubricate the clutch discs.

When the clutch 1 is in the disengaged condition shown in FIG. 2, therotatable sleeve 14 in moved by the disengaging member 13 away from theclutch plate 3 axially to the right as seen in FIG. 2. The guide wheel11 is thus moved to its clutch-disengaged position 21 and it operates tofeed the oil stream 20 along a path 22 against the pump wheel 12 duringthe disengaged state of the clutch. Accordingly, oil will no longerreach the clutch discs 4 and as a result drag moment is prevented. Atthe same time, the oil is deflected in the axial direction along thepath 22 as a result of impingement along the axial curvature 25 and itis accelerated. Due to the work which is performed during thisoccurrence, a brake torque is developed on the clutch plate 3 and thistorque acts to provide a braking action and thus essentially constitutesa clutch brake.

The oil is conducted axially away from the clutch housing 2 due to theaxial curvature 25 and back to the suction side 17 of the oil pump 16.Here the oil becomes available for repeated redistribution to the guidewheel 11. The oil stream 20 consequently flows in an uninterruptedmanner while the clutch is engaged as well as during the time that theclutch is disengaged.

If the clutch 1 is to be again engaged, for example after completion ofa shifting operation, then the disengaging member 14 is balanced and thediaphragm spring 7 presses the pressure plate 5 against the clutch disc4 once again. The rotatable sleeve 14 with the guide wheel 11 which isplaced at its end will move again toward the clutch plate 3 and the oilstream 20 will be again conducted against the deflector 10, aspreviously described. Of course, disengagement and braking action cansubsequently once again be effected.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:
 1. A clutch assembly for vehicles comprising:aclutch housing; a clutch in said housing, said clutch including clutchdisc means, spring means actuating said clutch disc means anddisengagement means coupled with said spring means and movable relativeto said clutch disc means between a first position for effectingengagement of said clutch and a second position for effectingdisengagement of said clutch; pump means structurally associated withsaid disengagement means for supplying fluid for said clutch in a fluidstream; deflector means for directing said fluid to said clutch discmeans; pump wheel means rotatively affixed with said clutch disc meansarranged relative to said deflector means for deflecting said fluidstream away from said clutch disc means; and guide wheel means connectedfor movement with said disengagement means, said guide wheel meansoperating when said disengagement means is in said first position todirect said fluid stream to said deflector means for delivery to saidclutch disc means and when said disengagement means is in said secondposition to divert said fluid stream to said pump wheel means fordirecting said fluid stream away from said clutch disc means forrecirculation through said pump means.
 2. A clutch according to claim 1wherein said guide wheel means is concentrically arranged in said clutchand operates to feed said fluid radially outwardly, said pump wheelmeans being configured with a curvature to deflect said fluid in theaxial direction of said clutch when said clutch is in the disengagedstate.
 3. A clutch assembly according to claim 2 wherein said curvatureis arranged in the vicinity of said clutch disc means and operates todivert said fluid stream away from said clutch.